A variety of devices are used to remove or reduce odors from air in restrooms and bathrooms. Ceiling fans are one example of such devices. Other examples include air filtration devices that remove odors from the vicinity of a toilet, including the bowl of the toilet. Some devices rely on the use of an electrically operated fan or suction apparatus to remove the air. The continuous operation of the fan or suction apparatus is typically not desirable because of the wear on the motor or other mechanical and electrical components of the fan or suction device and/or the continuous use of electricity.
Some conventional air filtration devices are designed for placement outside the toilet or attached to the toilet. One disadvantage of these devices is that the device is exposed and may not be aesthetically acceptable and/or may be subject to tampering. Other conventional air filtration devices are designed for operation in the toilet, however, many of these devices require modification (often extensive) of the toilet and/or a specially constructed toilet. For example, the device may require sealing of the toilet tank, attaching additional hoses or pipes to the toilet, and/or forming sensor windows in the tank or other portion of the toilet. These devices are typically not convenient or suitable for retrofitting existing toilets.
A number of air filtration devices have been developed that utilize switches to turn on and off the fan or suction device. Manual switches may be operated by a user, but are typically inconvenient. Accordingly, devices with automatic switches have been developed. One conventional type of switch is a pressure switch. The switch may be positioned, for example, underneath the toilet seat. The switch is actuated when a user sits on the toilet and released when the user stands up. A disadvantage of this type of pressure switch is that it is exposed and can be damaged, vandalized, or rendered nonfunctional by dirt, dust, or other contaminants.
Another type of conventional switch is an infrared sensor. Infrared light is emitted by an infrared source, such as a light emitting diode (LED), and reflected by a user to an infrared detector, such as a photocell. The use of infrared detection has several limitations. First, infrared radiation cannot penetrate most materials because of the short wavelength of the radiation. Thus, infrared emitters and detectors are typically either exposed or are positioned behind a window made of material that is transparent to infrared radiation. In addition, infrared sensors can be inadvertently or purposefully blocked by the presence of material, such as paper, dust, or cloth, in front of the emitter or detector.
Another disadvantage of infrared detection is that the reflectivity of objects, such as clothing, varies widely. Thus, the infrared detector must be sensitive to a wide variation in the strength of reflected signals. There is a risk that the detector may fail to detect a user with clothing or other articles that absorb or only weakly reflect infrared radiation. Furthermore, conventional infrared sensors do not discriminate with respect to distance of an object from the sensor. Thus, an infrared sensor might not discriminate between a person using a toilet and someone standing close to the toilet. These disadvantages of infrared detectors may cause faulty responses by the toilet ventilation device (e.g., continuous or intermittent operation of the fan or suction device).